In a way property taxes are a little like rent in that the tax is an ongoing payment that the owner is required to pay or face penalties up to and including the government taking the property and selling it to collect the back taxes.
The most common type of property tax today is the real estate property tax which is based upon the value of the land and improvements (buildings and any other physical improvements that are unmovable). Real estate property taxes are a major (often the major) source of tax revenue for local governments and smaller jurisdictions such as school districts. However, county, state and even the Federal Government can, and in some cases do, levy property taxes on real estate.
Failure to pay property taxes can result in the real estate being taken by the governmental jurisdiction levying the tax and sold to collect the unpaid taxes.
In many jurisdictions the unpaid taxes rather than the property itself are sold. In this case the unpaid taxes are paid by an outside buyer who usually purchases the taxes at a tax auction held by the taxing entity. In return for paying the unpaid taxes, the buyer receives a lien on the property which makes it nearly impossible for the owner of the property to obtain or refinance a mortgage or other type of loan using the property as collateral as the holder of the lien is entitled to a refund of the taxes he paid (and, depending on the laws of the state, may also be able to collect interest on the amount he paid for the taxes) when the property is sold. Further, the owner of the tax lien is legally entitled to be paid first out of the sale proceeds leaving what, if any, funds left for other lenders and the seller.